Electrooptical system



p 1936- J. -J. ROGAN I 2,055,088

. ELECTROOPTICAL SYSTEM Filed Nov. ,22, 1929 amoewtoz Patented Sept. 22, '1936 UNITED STATES ELECTROOPTICAL SYSTEM:

John J. Rogan, Elmhurst, N. Y., assignor to Hygrade Sylvania Corporation, Salem, Mass, a

corporation of Massachusetts Application November 22, 1929, Serial No. 409,005 7 i 9 Claims.

, This invention relates to electro-optical systems and with particularity to methods and means for translating currents into visual representations. i The invention is in the nature of an improvement on the type of system disclosed in copending application of John J. Rogan, Serial No. 409,002, filed Nov. 22, 1929. There is disclosed in said application a system of television wherein two separate light sources are employed at the receiving station, one of constant and high intensity, and the other of varying intensity. The principal object of the present invention is to provide a novel arrangement of lights at the receiving station of a television system whereby greater apparentcontrast is secured between the light and dark areas of the reproduced image.

Another object of the invention is to provide a novel method of combining the efiectsof a constant intensity light source and a varying inten- 'sity light source in the reproduction .of a visual 35 system and wherein for a given transmission level, more pronounced visual effects are produced at the receiving station.

Other features and advantages not specifically enumerated will be apparent after a considera- 40 tion of the following descriptions and .theappended claims. While thefeatures and objects of the invention will-be disclosed in connection with certain well-known types of apparatus, it will be understood that the invention is not :4 limited thereto but that this apparatus is used merely for the purpose of illustrating preferred modes of carrying out the inventive concept.

Accordingly, i

Fig. 1 of the drawing illustrates in diagram- 50 matic fashion one manner of reproducing visual representations according to the invention.

Fig. 2 shows a modified form of reproducing system.

Fig. 3 shows a still further modification of the 55 system disclosed in Fig. 1.

Referring to Fig. 1, there is shown in dia'grammatic form a reproducing arrangement suitable for a television system wherein the numeral 1 represents a light source which is adapted to have its intensity varied in'accordance with image 5 currents received over the transmission channel 2. For example, oneknown type of lamp suitable for this purpose includes a pair of spaced electrodes enclosed within an atmosphere of neon, which when excited gives off a pinkish-red 10 color. The light from lamp} -is projected by means of a suitable optical system} upon'a suit,- able surface 4 such as a groundglass screen, which may be viewed from either the front or rearsides, preferablythe latter. The illuminated l5 field is representedin Fig. l'by the dotted square 5, which may be of any size consistent with the detail required and the intensityof illumination fromlamp I.

As the varying image currents act upon lamp l, 20 there is projected upon the screen! a light spot of uniform dimensions, but of an intensity or light distribution varying in accordance with the image currents. In theIcase of a neon lamp the screen will therefore appear to be illuminated with a pinkish-red color.

Situated on one side of the screen 4, preferably on the same side as lamp I, although this is not absolutely necessary, is a source of light 6 of constant and preferably high intensity such as an arc lamp or the like. The light from lamp'li i is projected by a'suitable optical system I .upon a .portion ofthe periphery of scanning disc of the usual or Nipkow type, althougha lens disc of the type shown in Jenkins Patent No. 1,679,086 may be employed. When'the ,discisnot interposed between the light Band screen 4, the light from lamplfi is soadjusted as to produce a. light field of the same dimensionsias' that producedby lamp. 1 However, when the disc is interposed and rotated 40 in synchronisrn with .a,corresponding analyzing device at the sending station'in the. well known manner, the light from lamp 6 covers the field'5 in the form of a rapidly moving SpOLWhich h ever due: to its rapidity causes the field apparently to be entirely illuminated' f' As is well .known, the light from a neon lamp has a characteristiccolor which for certain purposesmay be undesirable or even tiresome. In order to overcome these and other defects, and

at the same time increase the apparent contrast between the picture field background and the reproduced images, it is preferable to so modify the constant intensity light from source 6 so as to make it complementary to that from source I.

reflecting substantially all the rays from sources 4 and 5, although it may be prepared to act as a selective reflector so far as the light from source 6 is concerned.

Furthermore, while a neon lamp or reddish light is used forsource I, it will be understood that any other color of light may be employed so long as it is complementary, or at least combines with the light from source 6 to heighten the apparent contrast of the reproduced image. f'jReferring to Fig. 2, there is shown another manner of combining the light sources; Numeral lfi representsja sourceof light, preferably of high and constant intensity, the rays of which are projected through "the sca'nningdisc l l by a suitablebpticalsystem. Positioned on the opposite side ofthe disc isa glow discharge lamp-screen :l2'of the type disclosed in co-pending application Serial No. 409,004. Located in front of screen I2 is ajsuitable optical system through which the observer mayview the light from source as well-as the-light from lamp-screen l2. As pointed out in the above-noted application, the observer receives the sensation -of 'movement from the source l0 (through {the intermediary of disc H) and also a sensation of varying brilliancy due to the lamp "I? which is energized under control of the incoming image currents. Inorder that the practicing the inventive "concept.

apparent brilliancy or heightened contrast may beach'ievedit is preferred to so design the lamp screen I? either by the gas content voltage, 'etc., that'th'e rays therefrom 'arecomplementary to *those emitted by the source 10." Thus if a neon gas content isiemployed forlamp I 2 and lamp 7| 0 emits ra'ys near theblueendof the spectrum, the image will appear in the form of variations between white and red or "orangawhereas in the ordinary "syst'emnsing a single light source the variation is between different brilliancies of the 's'amecolor. It will be understoodof course that any other combination of light sources may be employed? J 1 s Fig. '3fishowsa still further arrangement for I n this embodiment the source 13 'corresponds'to the sources 6 and l'0 (Figs.J1 and 2) and disc 14 is similar to discs 8 and 1 I. The incoming image currents however( after "being suitably'amplified) are appli 'edto a lamp 15 which gives forth rays complefmentary to those from source l3. Interposed between "the observing optical system "I 6 and" the disc I4 is a so-calledtransparent-mirror or 'totahreflecting prism 'l1'.1 Since the source 13 is in alignmentwith "the optical system IS, the rays therefrom maybe seen directlythrough mirror l1, while the raysfr'om source 15 reach'the 'observers eye byrefle'ctionfrom mirror l5. There isthusproduceda combined visual sensation of movement and "varying intensity using complementarycolorsources.

while "only three modes of e the fight 7 for optically and concurrently combining both said lights, the last-mentioned means including ascreen to which both lights are separately and simultaneously applied.

2. Means according to claim 1 in which both 7 sai'd'lights are complementary in color.

13. The method of television which comprises producing a stationary reddish light beam, simultaneously and separatelyapplying to a screen'together with said reddish beam a beam from an: other source of a color complementary thereto, moving one of said beams over a screen to scan the same, and varying the intensity of only the stationary beam in accordance with received image currents while maintaining the other beam constant.

4. Means for reproducing visual representations at a distance including a stationary light beam, a movable light beam, said light beams being of different wave-bands, means for varying only one beam by received image currentswhi le maintaining the other beam substantially constant and means for optically combining said beams, the "last-mentioned means including a screen to which both beams are simultaneously and separately applied.

5. Means according'to claim 4 in which said li-ghtbeams are substantially complementary.-

6. Means for reproducing visual representations at a distance including a moving light spot of constant intensity, astationary light spot of different color from the moving spot, means for simultaneously and separately applied.

7. Means according to claim 6 in which said spotsare substantially complementary in' color.

8. In an image reproducing system, a moving light spot, a stationarylight spot, means for con- 7 ,trolling one of "said spots by received image-currents, and means including a transparent for optically combining said spots. V

"9. In an electro-optical system employing a mirror scanning device the method of pr'otlucing an image under control "'of received image currents which comprises illuminating an entire translucent screen with a stationary artificial beam, simultaneously and separately illuminating said screen with another beam of'elemental cross sec- 'tion and constant intensity, moving the last mentioned beam in a point by point fashion to cover theentire screen, and simultaneously varyingthe intensity of the first mentioned beam under centrol of received image currents.

oint J. ROGAN. 

